&DRIFT: TIMING


electron

  These are the electrons you wish to select for output. One
  can either specify these by a sequence number or with such
  keywords as LAST, ONE-BUT-LAST etc.

  This should be approximately the threshold of the electronics,
  but since electronics usually doesn't trigger on a well
  defined electron, one can't obtain a too accurate resolution
  from this kind of instruction. If resolution estimates are
  required, one should compute signals and process these by
  an electronics simulation program.

  Default: only the 5th electron.

TIME-WINDOW

  Specifies the time window of all arrival time histograms, both
  of the selected electron and of all electrons. If you do not
  specify a time window, then all timing histograms are given a
  range automatically.

X-RANGE

  The part of the AREA to be covered by the tracks.

  Tracks are generated uniformly over this x-range. The
  WEIGHTING-FUNCTION can be used to assign probabilities
  to the various x values.

  Default: the entire x-range of the AREA.

Y-RANGE

  The vertical extent of the tracks. This parameter is less
  trivial than it might appear: if the range does not cover
  the full acceptance boundaries of the wire, the program
  will give wrong results for late electrons. If the range
  is chosen too small, the waste of CPU time is considerable
  and also the accuracy may suffer if the LINES parameter
  does not compensate.

  Default: the entire y-range of the AREA.

ANGLE-RANGE

  The range of angles of the tracks with respect to the vertical.

  Tracks will be generated according to a uniform distribution
  over this angular range. The WEIGHTING-FUNCTION can be used to
  attribute a probability to each angle.

  One may also enter a single angle if tracks are to be
  generated only at that angle.

  Default: only vertical tracks are generated.

MONTE-CARLO-DRIFT

  Specifying this option requests the use of Monte Carlo style
  drift line integration in which diffusion is accounted for on
  a step by step basis.

  Each electron of a cluster is in this case drifted separately.

  When using this option, you have to be sure that the time
  or distance interval for Monte Carlo integration (see the
  INTEGRATION-PARAMETERS statement) has been set to a reasonable
  value.

  Default: Runge-Kutta-Fehlberg integration is used.

ATTACHMENT

  Requests that attachment data is taken into account.

  Default: attachment data is not taken into account.

WEIGHTING-FUNCTION

  A function of X (x-coordinate of the track) and ANGLE (the
  inclination angle of the track in degrees) which is used to
  assign a probability to tracks with a given (x,angle) pair.

  Tracks are generated uniformly within the X-RANGE and the
  ANGLE-RANGE.

  Default: a weight of 1 is assigned to each track.

bins

  The number of bins in the histograms used to compute the
  time at which the selected histogram has a given probability
  to have arrived - the mean arrival time is computed directly
  without histogram.

  Default: half of MXLIST, usually 100 bins.

KEEP-HISTOGRAMS

  This option can be used to store the arrival time histograms
  for later study. The histograms are made accessible via global
  variable names that are displayed while the command is carried
  out (SELECTED and ALL).

  If (1) the instruction is placed in the body of a DO loop and
  (2) these global variables are used in arithmetic or in IF
  conditions, then you have to declare the global variables before
  the DO loop by assigning them an (arbitrary value). Declaring is
  not required if the variables are only used outside a DO loop,
  e.g. in SAY statements or in procedure calls.

  Default: histograms are not kept.

loops

  The number of Monte Carlo loops over track generation. These
  loops can consume considerable CPU time since the drift times,
  diffusion coefficients etc are computed for each drift line
  individually (in contrast the ARRIVAL which uses interpolation).

  Default: 1000.

plot_options

  Garfield can be asked to output for each track the timing
  histograms for all (PLOT-OVERALL) and the selected
  electron (PLOT-SELECTED-ELECTRON). Both are by default
  not plotted.

print_options

  The timing histograms for the selected electron and for
  all electrons are printed out at your request. In the printout,
  additional information such as the mean and width are provided.
  These quantities are computed from the entries themselves, not
  from the accumulated bin contents. The internal arithmetic is
  done in double precision.

Keyword index. Formatted on 10/11/98.